The buttstock assembly presently employed in connection with the M-16 rifle, which is illustrated in U.S. Pat. No. 3,618,248, embodies an exterior shell and a molded core therein which defines a cylindrical through volume or aperture extending longitudinally along the top of the buttstock and a centrally located stowage compartment. The cylindrical aperture received lower receiver extension in which a buffer assembly is mounted and the stowage compartment accommodates cleaning and servicing equipment necessary to maintain the rifle. The lower receiver extension is threadably secured to an attachment ring integral with the lower receiver.
The basic difficulty with the aforedescribed buttstock is that certain parts in the lower receiver are subjected to concentrated loads when the buttstock of the rifle is subject to impact loading. For example, when the buttstock engages the ground with substantial impact, the attachment ring has a tendency to fail.